1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use std::cmp::{min, Ordering};
13 use std::iter::{repeat, ExactSizeIterator};
15 use syntax::{ast, ptr};
16 use syntax::codemap::{BytePos, CodeMap, Span};
17 use syntax::parse::classify;
19 use {Indent, Shape, Spanned};
20 use chains::rewrite_chain;
21 use codemap::{LineRangeUtils, SpanUtils};
22 use comment::{combine_strs_with_missing_comments, contains_comment, recover_comment_removed,
23 rewrite_comment, rewrite_missing_comment, FindUncommented};
24 use config::{Config, ControlBraceStyle, IndentStyle, MultilineStyle, Style};
25 use items::{span_hi_for_arg, span_lo_for_arg};
26 use lists::{definitive_tactic, itemize_list, shape_for_tactic, struct_lit_formatting,
27 struct_lit_shape, struct_lit_tactic, write_list, DefinitiveListTactic, ListFormatting,
28 ListItem, ListTactic, Separator, SeparatorPlace, SeparatorTactic};
29 use macros::{rewrite_macro, MacroArg, MacroPosition};
30 use patterns::{can_be_overflowed_pat, TuplePatField};
31 use rewrite::{Rewrite, RewriteContext};
32 use string::{rewrite_string, StringFormat};
33 use types::{can_be_overflowed_type, rewrite_path, PathContext};
34 use utils::{binary_search, colon_spaces, contains_skip, extra_offset, first_line_width,
35 inner_attributes, last_line_extendable, last_line_width, left_most_sub_expr, mk_sp,
36 outer_attributes, paren_overhead, semicolon_for_stmt, stmt_expr,
37 trimmed_last_line_width, wrap_str};
38 use vertical::rewrite_with_alignment;
39 use visitor::FmtVisitor;
41 impl Rewrite for ast::Expr {
42 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
43 format_expr(self, ExprType::SubExpression, context, shape)
47 #[derive(Copy, Clone, PartialEq)]
56 context: &RewriteContext,
59 skip_out_of_file_lines_range!(context, expr.span);
61 if contains_skip(&*expr.attrs) {
62 return Some(context.snippet(expr.span()));
65 let expr_rw = match expr.node {
66 ast::ExprKind::Array(ref expr_vec) => rewrite_array(
67 expr_vec.iter().map(|e| &**e),
68 mk_sp(context.codemap.span_after(expr.span, "["), expr.span.hi()),
73 ast::ExprKind::Lit(ref l) => match l.node {
74 ast::LitKind::Str(_, ast::StrStyle::Cooked) => {
75 rewrite_string_lit(context, l.span, shape)
78 context.snippet(expr.span),
79 context.config.max_width(),
83 ast::ExprKind::Call(ref callee, ref args) => {
84 let inner_span = mk_sp(callee.span.hi(), expr.span.hi());
85 rewrite_call_with_binary_search(
88 &args.iter().map(|x| &**x).collect::<Vec<_>>()[..],
93 ast::ExprKind::Paren(ref subexpr) => rewrite_paren(context, subexpr, shape),
94 ast::ExprKind::Binary(ref op, ref lhs, ref rhs) => {
95 // FIXME: format comments between operands and operator
100 &format!(" {} ", context.snippet(op.span)),
106 ast::ExprKind::Unary(ref op, ref subexpr) => rewrite_unary_op(context, op, subexpr, shape),
107 ast::ExprKind::Struct(ref path, ref fields, ref base) => rewrite_struct_lit(
111 base.as_ref().map(|e| &**e),
115 ast::ExprKind::Tup(ref items) => rewrite_tuple(
117 &items.iter().map(|x| &**x).collect::<Vec<_>>()[..],
121 ast::ExprKind::If(..) |
122 ast::ExprKind::IfLet(..) |
123 ast::ExprKind::ForLoop(..) |
124 ast::ExprKind::Loop(..) |
125 ast::ExprKind::While(..) |
126 ast::ExprKind::WhileLet(..) => to_control_flow(expr, expr_type)
127 .and_then(|control_flow| control_flow.rewrite(context, shape)),
128 ast::ExprKind::Block(ref block) => {
130 ExprType::Statement => {
131 if is_unsafe_block(block) {
132 block.rewrite(context, shape)
133 } else if let rw @ Some(_) = rewrite_empty_block(context, block, shape) {
134 // Rewrite block without trying to put it in a single line.
137 let prefix = try_opt!(block_prefix(context, block, shape));
138 rewrite_block_with_visitor(context, &prefix, block, shape)
141 ExprType::SubExpression => block.rewrite(context, shape),
144 ast::ExprKind::Match(ref cond, ref arms) => {
145 rewrite_match(context, cond, arms, shape, expr.span, &expr.attrs)
147 ast::ExprKind::Path(ref qself, ref path) => {
148 rewrite_path(context, PathContext::Expr, qself.as_ref(), path, shape)
150 ast::ExprKind::Assign(ref lhs, ref rhs) => {
151 rewrite_assignment(context, lhs, rhs, None, shape)
153 ast::ExprKind::AssignOp(ref op, ref lhs, ref rhs) => {
154 rewrite_assignment(context, lhs, rhs, Some(op), shape)
156 ast::ExprKind::Continue(ref opt_ident) => {
157 let id_str = match *opt_ident {
158 Some(ident) => format!(" {}", ident.node),
159 None => String::new(),
162 format!("continue{}", id_str),
163 context.config.max_width(),
167 ast::ExprKind::Break(ref opt_ident, ref opt_expr) => {
168 let id_str = match *opt_ident {
169 Some(ident) => format!(" {}", ident.node),
170 None => String::new(),
173 if let Some(ref expr) = *opt_expr {
174 rewrite_unary_prefix(context, &format!("break{} ", id_str), &**expr, shape)
177 format!("break{}", id_str),
178 context.config.max_width(),
183 ast::ExprKind::Yield(ref opt_expr) => if let Some(ref expr) = *opt_expr {
184 rewrite_unary_prefix(context, "yield ", &**expr, shape)
186 wrap_str("yield".to_string(), context.config.max_width(), shape)
188 ast::ExprKind::Closure(capture, ref fn_decl, ref body, _) => {
189 rewrite_closure(capture, fn_decl, body, expr.span, context, shape)
191 ast::ExprKind::Try(..) |
192 ast::ExprKind::Field(..) |
193 ast::ExprKind::TupField(..) |
194 ast::ExprKind::MethodCall(..) => rewrite_chain(expr, context, shape),
195 ast::ExprKind::Mac(ref mac) => {
196 // Failure to rewrite a marco should not imply failure to
197 // rewrite the expression.
198 rewrite_macro(mac, None, context, shape, MacroPosition::Expression).or_else(|| {
200 context.snippet(expr.span),
201 context.config.max_width(),
206 ast::ExprKind::Ret(None) => {
207 wrap_str("return".to_owned(), context.config.max_width(), shape)
209 ast::ExprKind::Ret(Some(ref expr)) => {
210 rewrite_unary_prefix(context, "return ", &**expr, shape)
212 ast::ExprKind::Box(ref expr) => rewrite_unary_prefix(context, "box ", &**expr, shape),
213 ast::ExprKind::AddrOf(mutability, ref expr) => {
214 rewrite_expr_addrof(context, mutability, expr, shape)
216 ast::ExprKind::Cast(ref expr, ref ty) => {
217 rewrite_pair(&**expr, &**ty, "", " as ", "", context, shape)
219 ast::ExprKind::Type(ref expr, ref ty) => {
220 rewrite_pair(&**expr, &**ty, "", ": ", "", context, shape)
222 ast::ExprKind::Index(ref expr, ref index) => {
223 rewrite_index(&**expr, &**index, context, shape)
225 ast::ExprKind::Repeat(ref expr, ref repeats) => {
226 let (lbr, rbr) = if context.config.spaces_within_square_brackets() {
231 rewrite_pair(&**expr, &**repeats, lbr, "; ", rbr, context, shape)
233 ast::ExprKind::Range(ref lhs, ref rhs, limits) => {
234 let delim = match limits {
235 ast::RangeLimits::HalfOpen => "..",
236 ast::RangeLimits::Closed => "...",
239 fn needs_space_before_range(context: &RewriteContext, lhs: &ast::Expr) -> bool {
241 ast::ExprKind::Lit(ref lit) => match lit.node {
242 ast::LitKind::FloatUnsuffixed(..) => {
243 context.snippet(lit.span).ends_with('.')
251 match (lhs.as_ref().map(|x| &**x), rhs.as_ref().map(|x| &**x)) {
252 (Some(lhs), Some(rhs)) => {
253 let sp_delim = if context.config.spaces_around_ranges() {
254 format!(" {} ", delim)
255 } else if needs_space_before_range(context, lhs) {
256 format!(" {}", delim)
260 rewrite_pair(&*lhs, &*rhs, "", &sp_delim, "", context, shape)
262 (None, Some(rhs)) => {
263 let sp_delim = if context.config.spaces_around_ranges() {
264 format!("{} ", delim)
268 rewrite_unary_prefix(context, &sp_delim, &*rhs, shape)
270 (Some(lhs), None) => {
271 let sp_delim = if context.config.spaces_around_ranges() {
272 format!(" {}", delim)
276 rewrite_unary_suffix(context, &sp_delim, &*lhs, shape)
278 (None, None) => wrap_str(delim.into(), context.config.max_width(), shape),
281 // We do not format these expressions yet, but they should still
282 // satisfy our width restrictions.
283 ast::ExprKind::InPlace(..) | ast::ExprKind::InlineAsm(..) => wrap_str(
284 context.snippet(expr.span),
285 context.config.max_width(),
288 ast::ExprKind::Catch(ref block) => {
289 if let rw @ Some(_) = rewrite_single_line_block(context, "do catch ", block, shape) {
293 let budget = shape.width.checked_sub(9).unwrap_or(0);
297 try_opt!(block.rewrite(&context, Shape::legacy(budget, shape.indent)))
304 .and_then(|expr_str| {
305 recover_comment_removed(expr_str, expr.span, context, shape)
307 .and_then(|expr_str| {
308 let attrs = outer_attributes(&expr.attrs);
309 let attrs_str = try_opt!(attrs.rewrite(context, shape));
311 attrs.last().map_or(expr.span.lo(), |attr| attr.span.hi()),
314 combine_strs_with_missing_comments(context, &attrs_str, &expr_str, span, shape, false)
318 pub fn rewrite_pair<LHS, RHS>(
324 context: &RewriteContext,
331 let sep = if infix.ends_with(' ') { " " } else { "" };
332 let infix = infix.trim_right();
333 let lhs_overhead = shape.used_width() + prefix.len() + infix.len();
334 let lhs_shape = Shape {
335 width: try_opt!(context.config.max_width().checked_sub(lhs_overhead)),
338 let lhs_result = try_opt!(
339 lhs.rewrite(context, lhs_shape)
340 .map(|lhs_str| format!("{}{}{}", prefix, lhs_str, infix))
343 // Try to the both lhs and rhs on the same line.
344 let rhs_orig_result = shape
345 .offset_left(last_line_width(&lhs_result) + suffix.len() + sep.len())
346 .and_then(|rhs_shape| rhs.rewrite(context, rhs_shape));
347 if let Some(ref rhs_result) = rhs_orig_result {
348 // If the rhs looks like block expression, we allow it to stay on the same line
349 // with the lhs even if it is multi-lined.
350 let allow_same_line = rhs_result
353 .map(|first_line| first_line.ends_with('{'))
355 if !rhs_result.contains('\n') || allow_same_line {
356 return Some(format!("{}{}{}{}", lhs_result, sep, rhs_result, suffix));
360 // We have to use multiple lines.
361 // Re-evaluate the rhs because we have more space now:
362 let rhs_shape = match context.config.control_style() {
364 try_opt!(shape.sub_width(suffix.len() + prefix.len())).visual_indent(prefix.len())
367 // Try to calculate the initial constraint on the right hand side.
368 let rhs_overhead = shape.rhs_overhead(context.config);
370 Shape::indented(shape.indent.block_indent(context.config), context.config)
371 .sub_width(rhs_overhead)
375 let rhs_result = try_opt!(rhs.rewrite(context, rhs_shape));
379 rhs_shape.indent.to_string(context.config),
385 pub fn rewrite_array<'a, I>(
388 context: &RewriteContext,
390 trailing_comma: bool,
393 I: Iterator<Item = &'a ast::Expr>,
395 let bracket_size = if context.config.spaces_within_square_brackets() {
401 let nested_shape = match context.config.array_layout() {
402 IndentStyle::Block => try_opt!(
405 .block_indent(context.config.tab_spaces())
406 .with_max_width(context.config)
409 IndentStyle::Visual => try_opt!(
411 .visual_indent(bracket_size)
412 .sub_width(bracket_size * 2)
416 let items = itemize_list(
420 |item| item.span.lo(),
421 |item| item.span.hi(),
422 |item| item.rewrite(context, nested_shape),
426 ).collect::<Vec<_>>();
428 if items.is_empty() {
429 if context.config.spaces_within_square_brackets() {
430 return Some("[ ]".to_string());
432 return Some("[]".to_string());
436 let has_long_item = items
438 .any(|li| li.item.as_ref().map(|s| s.len() > 10).unwrap_or(false));
440 let mut tactic = match context.config.array_layout() {
441 IndentStyle::Block => {
442 // FIXME wrong shape in one-line case
443 match shape.width.checked_sub(2 * bracket_size) {
446 ListTactic::LimitedHorizontalVertical(context.config.array_width());
447 definitive_tactic(&items, tactic, Separator::Comma, width)
449 None => DefinitiveListTactic::Vertical,
452 IndentStyle::Visual => if has_long_item || items.iter().any(ListItem::is_multiline) {
455 ListTactic::LimitedHorizontalVertical(context.config.array_width()),
460 DefinitiveListTactic::Mixed
463 let ends_with_newline = tactic.ends_with_newline(context.config.array_layout());
464 if context.config.array_horizontal_layout_threshold() > 0 &&
465 items.len() > context.config.array_horizontal_layout_threshold()
467 tactic = DefinitiveListTactic::Mixed;
470 let fmt = ListFormatting {
473 trailing_separator: if trailing_comma {
474 SeparatorTactic::Always
475 } else if context.inside_macro || context.config.array_layout() == IndentStyle::Visual {
476 SeparatorTactic::Never
478 SeparatorTactic::Vertical
480 separator_place: SeparatorPlace::Back,
482 ends_with_newline: ends_with_newline,
483 preserve_newline: false,
484 config: context.config,
486 let list_str = try_opt!(write_list(&items, &fmt));
488 let result = if context.config.array_layout() == IndentStyle::Visual ||
489 tactic == DefinitiveListTactic::Horizontal
491 if context.config.spaces_within_square_brackets() && !list_str.is_empty() {
492 format!("[ {} ]", list_str)
494 format!("[{}]", list_str)
499 nested_shape.indent.to_string(context.config),
501 shape.block().indent.to_string(context.config)
508 // Return type is (prefix, extra_offset)
509 fn rewrite_closure_fn_decl(
510 capture: ast::CaptureBy,
511 fn_decl: &ast::FnDecl,
514 context: &RewriteContext,
516 ) -> Option<(String, usize)> {
517 let mover = if capture == ast::CaptureBy::Value {
522 // 4 = "|| {".len(), which is overconservative when the closure consists of
523 // a single expression.
524 let nested_shape = try_opt!(try_opt!(shape.shrink_left(mover.len())).sub_width(4));
527 let argument_offset = nested_shape.indent + 1;
528 let arg_shape = try_opt!(nested_shape.offset_left(1)).visual_indent(0);
529 let ret_str = try_opt!(fn_decl.output.rewrite(context, arg_shape));
531 let arg_items = itemize_list(
533 fn_decl.inputs.iter(),
535 |arg| span_lo_for_arg(arg),
536 |arg| span_hi_for_arg(context, arg),
537 |arg| arg.rewrite(context, arg_shape),
538 context.codemap.span_after(span, "|"),
542 let item_vec = arg_items.collect::<Vec<_>>();
543 // 1 = space between arguments and return type.
544 let horizontal_budget = nested_shape
546 .checked_sub(ret_str.len() + 1)
548 let tactic = definitive_tactic(
550 ListTactic::HorizontalVertical,
554 let arg_shape = match tactic {
555 DefinitiveListTactic::Horizontal => try_opt!(arg_shape.sub_width(ret_str.len() + 1)),
559 let fmt = ListFormatting {
562 trailing_separator: SeparatorTactic::Never,
563 separator_place: SeparatorPlace::Back,
565 ends_with_newline: false,
566 preserve_newline: true,
567 config: context.config,
569 let list_str = try_opt!(write_list(&item_vec, &fmt));
570 let mut prefix = format!("{}|{}|", mover, list_str);
571 // 1 = space between `|...|` and body.
572 let extra_offset = extra_offset(&prefix, shape) + 1;
574 if !ret_str.is_empty() {
575 if prefix.contains('\n') {
577 prefix.push_str(&argument_offset.to_string(context.config));
581 prefix.push_str(&ret_str);
584 Some((prefix, extra_offset))
587 // This functions is pretty messy because of the rules around closures and blocks:
588 // FIXME - the below is probably no longer true in full.
589 // * if there is a return type, then there must be braces,
590 // * given a closure with braces, whether that is parsed to give an inner block
591 // or not depends on if there is a return type and if there are statements
593 // * if the first expression in the body ends with a block (i.e., is a
594 // statement without needing a semi-colon), then adding or removing braces
595 // can change whether it is treated as an expression or statement.
597 capture: ast::CaptureBy,
598 fn_decl: &ast::FnDecl,
601 context: &RewriteContext,
603 ) -> Option<String> {
604 let (prefix, extra_offset) = try_opt!(rewrite_closure_fn_decl(
612 // 1 = space between `|...|` and body.
613 let body_shape = try_opt!(shape.offset_left(extra_offset));
615 if let ast::ExprKind::Block(ref block) = body.node {
616 // The body of the closure is an empty block.
617 if block.stmts.is_empty() && !block_contains_comment(block, context.codemap) {
618 return Some(format!("{} {{}}", prefix));
621 // Figure out if the block is necessary.
622 let needs_block = block.rules != ast::BlockCheckMode::Default || block.stmts.len() > 1 ||
623 context.inside_macro ||
624 block_contains_comment(block, context.codemap) ||
625 prefix.contains('\n');
627 let no_return_type = if let ast::FunctionRetTy::Default(_) = fn_decl.output {
632 if no_return_type && !needs_block {
633 // block.stmts.len() == 1
634 if let Some(expr) = stmt_expr(&block.stmts[0]) {
635 if let Some(rw) = rewrite_closure_expr(expr, &prefix, context, body_shape) {
641 // Either we require a block, or tried without and failed.
642 rewrite_closure_block(block, &prefix, context, body_shape)
644 rewrite_closure_expr(body, &prefix, context, body_shape).or_else(|| {
645 // The closure originally had a non-block expression, but we can't fit on
646 // one line, so we'll insert a block.
647 rewrite_closure_with_block(context, body_shape, &prefix, body)
652 // Rewrite closure with a single expression wrapping its body with block.
653 fn rewrite_closure_with_block(
654 context: &RewriteContext,
658 ) -> Option<String> {
659 let block = ast::Block {
662 id: ast::NodeId::new(0),
663 node: ast::StmtKind::Expr(ptr::P(body.clone())),
667 id: ast::NodeId::new(0),
668 rules: ast::BlockCheckMode::Default,
671 rewrite_closure_block(&block, prefix, context, shape)
674 // Rewrite closure with a single expression without wrapping its body with block.
675 fn rewrite_closure_expr(
678 context: &RewriteContext,
680 ) -> Option<String> {
681 let mut rewrite = expr.rewrite(context, shape);
682 if classify::expr_requires_semi_to_be_stmt(left_most_sub_expr(expr)) {
683 rewrite = and_one_line(rewrite);
685 rewrite = rewrite.and_then(|rw| {
686 if context.config.multiline_closure_forces_block() && rw.contains('\n') {
692 rewrite.map(|rw| format!("{} {}", prefix, rw))
695 // Rewrite closure whose body is block.
696 fn rewrite_closure_block(
699 context: &RewriteContext,
701 ) -> Option<String> {
702 // Start with visual indent, then fall back to block indent if the
704 let block_threshold = context.config.closure_block_indent_threshold();
705 if block_threshold >= 0 {
706 if let Some(block_str) = block.rewrite(context, shape) {
707 if block_str.matches('\n').count() <= block_threshold as usize &&
708 !need_block_indent(&block_str, shape)
710 if let Some(block_str) = block_str.rewrite(context, shape) {
711 return Some(format!("{} {}", prefix, block_str));
717 // The body of the closure is big enough to be block indented, that
718 // means we must re-format.
719 let block_shape = shape.block();
720 let block_str = try_opt!(block.rewrite(context, block_shape));
721 Some(format!("{} {}", prefix, block_str))
724 fn and_one_line(x: Option<String>) -> Option<String> {
725 x.and_then(|x| if x.contains('\n') { None } else { Some(x) })
728 fn nop_block_collapse(block_str: Option<String>, budget: usize) -> Option<String> {
729 debug!("nop_block_collapse {:?} {}", block_str, budget);
730 block_str.map(|block_str| {
731 if block_str.starts_with('{') && budget >= 2 &&
732 (block_str[1..].find(|c: char| !c.is_whitespace()).unwrap() == block_str.len() - 2)
741 fn rewrite_empty_block(
742 context: &RewriteContext,
745 ) -> Option<String> {
746 if block.stmts.is_empty() && !block_contains_comment(block, context.codemap) && shape.width >= 2
748 return Some("{}".to_owned());
751 // If a block contains only a single-line comment, then leave it on one line.
752 let user_str = context.snippet(block.span);
753 let user_str = user_str.trim();
754 if user_str.starts_with('{') && user_str.ends_with('}') {
755 let comment_str = user_str[1..user_str.len() - 1].trim();
756 if block.stmts.is_empty() && !comment_str.contains('\n') &&
757 !comment_str.starts_with("//") && comment_str.len() + 4 <= shape.width
759 return Some(format!("{{ {} }}", comment_str));
766 fn block_prefix(context: &RewriteContext, block: &ast::Block, shape: Shape) -> Option<String> {
767 Some(match block.rules {
768 ast::BlockCheckMode::Unsafe(..) => {
769 let snippet = context.snippet(block.span);
770 let open_pos = try_opt!(snippet.find_uncommented("{"));
771 // Extract comment between unsafe and block start.
772 let trimmed = &snippet[6..open_pos].trim();
774 if !trimmed.is_empty() {
775 // 9 = "unsafe {".len(), 7 = "unsafe ".len()
776 let budget = try_opt!(shape.width.checked_sub(9));
779 try_opt!(rewrite_comment(
782 Shape::legacy(budget, shape.indent + 7),
790 ast::BlockCheckMode::Default => String::new(),
794 fn rewrite_single_line_block(
795 context: &RewriteContext,
799 ) -> Option<String> {
800 if is_simple_block(block, context.codemap) {
801 let expr_shape = Shape::legacy(shape.width - prefix.len(), shape.indent);
802 let expr_str = try_opt!(block.stmts[0].rewrite(context, expr_shape));
803 let result = format!("{}{{ {} }}", prefix, expr_str);
804 if result.len() <= shape.width && !result.contains('\n') {
811 fn rewrite_block_with_visitor(
812 context: &RewriteContext,
816 ) -> Option<String> {
817 if let rw @ Some(_) = rewrite_empty_block(context, block, shape) {
821 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
822 visitor.block_indent = shape.indent;
823 visitor.is_if_else_block = context.is_if_else_block;
825 ast::BlockCheckMode::Unsafe(..) => {
826 let snippet = context.snippet(block.span);
827 let open_pos = try_opt!(snippet.find_uncommented("{"));
828 visitor.last_pos = block.span.lo() + BytePos(open_pos as u32)
830 ast::BlockCheckMode::Default => visitor.last_pos = block.span.lo(),
833 visitor.visit_block(block, None);
834 Some(format!("{}{}", prefix, visitor.buffer))
837 impl Rewrite for ast::Block {
838 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
839 // shape.width is used only for the single line case: either the empty block `{}`,
840 // or an unsafe expression `unsafe { e }`.
841 if let rw @ Some(_) = rewrite_empty_block(context, self, shape) {
845 let prefix = try_opt!(block_prefix(context, self, shape));
847 let result = rewrite_block_with_visitor(context, &prefix, self, shape);
848 if let Some(ref result_str) = result {
849 if result_str.lines().count() <= 3 {
850 if let rw @ Some(_) = rewrite_single_line_block(context, &prefix, self, shape) {
860 impl Rewrite for ast::Stmt {
861 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
862 skip_out_of_file_lines_range!(context, self.span());
864 let result = match self.node {
865 ast::StmtKind::Local(ref local) => local.rewrite(context, shape),
866 ast::StmtKind::Expr(ref ex) | ast::StmtKind::Semi(ref ex) => {
867 let suffix = if semicolon_for_stmt(context, self) {
873 let shape = try_opt!(shape.sub_width(suffix.len()));
874 format_expr(ex, ExprType::Statement, context, shape).map(|s| s + suffix)
876 ast::StmtKind::Mac(..) | ast::StmtKind::Item(..) => None,
878 result.and_then(|res| {
879 recover_comment_removed(res, self.span(), context, shape)
884 // Rewrite condition if the given expression has one.
885 fn rewrite_cond(context: &RewriteContext, expr: &ast::Expr, shape: Shape) -> Option<String> {
887 ast::ExprKind::Match(ref cond, _) => {
889 let cond_shape = match context.config.control_style() {
890 Style::Legacy => try_opt!(shape.shrink_left(6).and_then(|s| s.sub_width(2))),
891 Style::Rfc => try_opt!(shape.offset_left(8)),
893 cond.rewrite(context, cond_shape)
895 ast::ExprKind::Block(ref block) if block.stmts.len() == 1 => {
896 stmt_expr(&block.stmts[0]).and_then(|e| rewrite_cond(context, e, shape))
898 _ => to_control_flow(expr, ExprType::SubExpression).and_then(|control_flow| {
900 String::from("\n") + &shape.indent.block_only().to_string(context.config);
902 .rewrite_cond(context, shape, &alt_block_sep)
903 .and_then(|rw| Some(rw.0))
908 // Abstraction over control flow expressions
910 struct ControlFlow<'a> {
911 cond: Option<&'a ast::Expr>,
912 block: &'a ast::Block,
913 else_block: Option<&'a ast::Expr>,
914 label: Option<ast::SpannedIdent>,
915 pat: Option<&'a ast::Pat>,
919 allow_single_line: bool,
920 // True if this is an `if` expression in an `else if` :-( hacky
925 fn to_control_flow<'a>(expr: &'a ast::Expr, expr_type: ExprType) -> Option<ControlFlow<'a>> {
927 ast::ExprKind::If(ref cond, ref if_block, ref else_block) => Some(ControlFlow::new_if(
931 else_block.as_ref().map(|e| &**e),
932 expr_type == ExprType::SubExpression,
936 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref else_block) => {
937 Some(ControlFlow::new_if(
941 else_block.as_ref().map(|e| &**e),
942 expr_type == ExprType::SubExpression,
947 ast::ExprKind::ForLoop(ref pat, ref cond, ref block, label) => {
948 Some(ControlFlow::new_for(pat, cond, block, label, expr.span))
950 ast::ExprKind::Loop(ref block, label) => {
951 Some(ControlFlow::new_loop(block, label, expr.span))
953 ast::ExprKind::While(ref cond, ref block, label) => {
954 Some(ControlFlow::new_while(None, cond, block, label, expr.span))
956 ast::ExprKind::WhileLet(ref pat, ref cond, ref block, label) => Some(
957 ControlFlow::new_while(Some(pat), cond, block, label, expr.span),
963 impl<'a> ControlFlow<'a> {
966 pat: Option<&'a ast::Pat>,
967 block: &'a ast::Block,
968 else_block: Option<&'a ast::Expr>,
969 allow_single_line: bool,
972 ) -> ControlFlow<'a> {
976 else_block: else_block,
985 allow_single_line: allow_single_line,
986 nested_if: nested_if,
992 block: &'a ast::Block,
993 label: Option<ast::SpannedIdent>,
995 ) -> ControlFlow<'a> {
1005 allow_single_line: false,
1012 pat: Option<&'a ast::Pat>,
1013 cond: &'a ast::Expr,
1014 block: &'a ast::Block,
1015 label: Option<ast::SpannedIdent>,
1017 ) -> ControlFlow<'a> {
1025 matcher: match pat {
1030 allow_single_line: false,
1038 cond: &'a ast::Expr,
1039 block: &'a ast::Block,
1040 label: Option<ast::SpannedIdent>,
1042 ) -> ControlFlow<'a> {
1052 allow_single_line: false,
1058 fn rewrite_single_line(
1061 context: &RewriteContext,
1063 ) -> Option<String> {
1064 assert!(self.allow_single_line);
1065 let else_block = try_opt!(self.else_block);
1066 let fixed_cost = self.keyword.len() + " { } else { }".len();
1068 if let ast::ExprKind::Block(ref else_node) = else_block.node {
1069 if !is_simple_block(self.block, context.codemap) ||
1070 !is_simple_block(else_node, context.codemap) ||
1071 pat_expr_str.contains('\n')
1076 let new_width = try_opt!(width.checked_sub(pat_expr_str.len() + fixed_cost));
1077 let expr = &self.block.stmts[0];
1078 let if_str = try_opt!(expr.rewrite(context, Shape::legacy(new_width, Indent::empty())));
1080 let new_width = try_opt!(new_width.checked_sub(if_str.len()));
1081 let else_expr = &else_node.stmts[0];
1083 try_opt!(else_expr.rewrite(context, Shape::legacy(new_width, Indent::empty())));
1085 if if_str.contains('\n') || else_str.contains('\n') {
1089 let result = format!(
1090 "{} {} {{ {} }} else {{ {} }}",
1097 if result.len() <= width {
1098 return Some(result);
1106 impl<'a> ControlFlow<'a> {
1109 context: &RewriteContext,
1111 alt_block_sep: &str,
1112 ) -> Option<(String, usize)> {
1113 // Do not take the rhs overhead from the upper expressions into account
1114 // when rewriting pattern.
1115 let new_width = context
1118 .checked_sub(shape.used_width())
1120 let fresh_shape = Shape {
1124 let constr_shape = if self.nested_if {
1125 // We are part of an if-elseif-else chain. Our constraints are tightened.
1126 // 7 = "} else " .len()
1127 try_opt!(fresh_shape.offset_left(7))
1132 let label_string = rewrite_label(self.label);
1133 // 1 = space after keyword.
1134 let offset = self.keyword.len() + label_string.len() + 1;
1136 let pat_expr_string = match self.cond {
1138 let cond_shape = match context.config.control_style() {
1139 Style::Legacy => try_opt!(constr_shape.shrink_left(offset)),
1140 Style::Rfc => try_opt!(constr_shape.offset_left(offset)),
1142 try_opt!(rewrite_pat_expr(
1152 None => String::new(),
1155 let brace_overhead =
1156 if context.config.control_brace_style() != ControlBraceStyle::AlwaysNextLine {
1162 let one_line_budget = context
1165 .checked_sub(constr_shape.used_width() + offset + brace_overhead)
1167 let force_newline_brace = context.config.control_style() == Style::Rfc &&
1168 (pat_expr_string.contains('\n') || pat_expr_string.len() > one_line_budget) &&
1169 !last_line_extendable(&pat_expr_string);
1171 // Try to format if-else on single line.
1172 if self.allow_single_line && context.config.single_line_if_else_max_width() > 0 {
1173 let trial = self.rewrite_single_line(&pat_expr_string, context, shape.width);
1175 if let Some(cond_str) = trial {
1176 if cond_str.len() <= context.config.single_line_if_else_max_width() {
1177 return Some((cond_str, 0));
1182 let cond_span = if let Some(cond) = self.cond {
1185 mk_sp(self.block.span.lo(), self.block.span.lo())
1188 // `for event in event`
1189 // Do not include label in the span.
1190 let lo = self.label.map_or(self.span.lo(), |label| label.span.hi());
1191 let between_kwd_cond = mk_sp(
1194 .span_after(mk_sp(lo, self.span.hi()), self.keyword.trim()),
1196 .map_or(cond_span.lo(), |p| if self.matcher.is_empty() {
1199 context.codemap.span_before(self.span, self.matcher.trim())
1203 let between_kwd_cond_comment = extract_comment(between_kwd_cond, context, shape);
1205 let after_cond_comment =
1206 extract_comment(mk_sp(cond_span.hi(), self.block.span.lo()), context, shape);
1208 let block_sep = if self.cond.is_none() && between_kwd_cond_comment.is_some() {
1210 } else if context.config.control_brace_style() == ControlBraceStyle::AlwaysNextLine ||
1218 let used_width = if pat_expr_string.contains('\n') {
1219 last_line_width(&pat_expr_string)
1221 // 2 = spaces after keyword and condition.
1222 label_string.len() + self.keyword.len() + pat_expr_string.len() + 2
1230 between_kwd_cond_comment.as_ref().map_or(
1231 if pat_expr_string.is_empty() || pat_expr_string.starts_with('\n') {
1239 after_cond_comment.as_ref().map_or(block_sep, |s| &**s)
1246 impl<'a> Rewrite for ControlFlow<'a> {
1247 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1248 debug!("ControlFlow::rewrite {:?} {:?}", self, shape);
1251 String::from("\n") + &shape.indent.block_only().to_string(context.config);
1252 let (cond_str, used_width) = try_opt!(self.rewrite_cond(context, shape, &alt_block_sep));
1253 // If `used_width` is 0, it indicates that whole control flow is written in a single line.
1254 if used_width == 0 {
1255 return Some(cond_str);
1258 let block_width = shape.width.checked_sub(used_width).unwrap_or(0);
1259 // This is used only for the empty block case: `{}`. So, we use 1 if we know
1260 // we should avoid the single line case.
1261 let block_width = if self.else_block.is_some() || self.nested_if {
1266 let block_shape = Shape {
1270 let mut block_context = context.clone();
1271 block_context.is_if_else_block = self.else_block.is_some();
1272 let block_str = try_opt!(rewrite_block_with_visitor(
1279 let mut result = format!("{}{}", cond_str, block_str);
1281 if let Some(else_block) = self.else_block {
1282 let shape = Shape::indented(shape.indent, context.config);
1283 let mut last_in_chain = false;
1284 let rewrite = match else_block.node {
1285 // If the else expression is another if-else expression, prevent it
1286 // from being formatted on a single line.
1287 // Note how we're passing the original shape, as the
1288 // cost of "else" should not cascade.
1289 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref next_else_block) => {
1290 ControlFlow::new_if(
1294 next_else_block.as_ref().map(|e| &**e),
1297 mk_sp(else_block.span.lo(), self.span.hi()),
1298 ).rewrite(context, shape)
1300 ast::ExprKind::If(ref cond, ref if_block, ref next_else_block) => {
1301 ControlFlow::new_if(
1305 next_else_block.as_ref().map(|e| &**e),
1308 mk_sp(else_block.span.lo(), self.span.hi()),
1309 ).rewrite(context, shape)
1312 last_in_chain = true;
1313 // When rewriting a block, the width is only used for single line
1314 // blocks, passing 1 lets us avoid that.
1315 let else_shape = Shape {
1316 width: min(1, shape.width),
1319 format_expr(else_block, ExprType::Statement, context, else_shape)
1323 let between_kwd_else_block = mk_sp(
1324 self.block.span.hi(),
1327 .span_before(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1329 let between_kwd_else_block_comment =
1330 extract_comment(between_kwd_else_block, context, shape);
1332 let after_else = mk_sp(
1335 .span_after(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1336 else_block.span.lo(),
1338 let after_else_comment = extract_comment(after_else, context, shape);
1340 let between_sep = match context.config.control_brace_style() {
1341 ControlBraceStyle::AlwaysNextLine | ControlBraceStyle::ClosingNextLine => {
1344 ControlBraceStyle::AlwaysSameLine => " ",
1346 let after_sep = match context.config.control_brace_style() {
1347 ControlBraceStyle::AlwaysNextLine if last_in_chain => &*alt_block_sep,
1354 between_kwd_else_block_comment
1356 .map_or(between_sep, |s| &**s),
1357 after_else_comment.as_ref().map_or(after_sep, |s| &**s)
1360 result.push_str(&try_opt!(rewrite));
1367 fn rewrite_label(label: Option<ast::SpannedIdent>) -> String {
1369 Some(ident) => format!("{}: ", ident.node),
1370 None => "".to_owned(),
1374 fn extract_comment(span: Span, context: &RewriteContext, shape: Shape) -> Option<String> {
1375 match rewrite_missing_comment(span, shape, context) {
1376 Some(ref comment) if !comment.is_empty() => Some(format!(
1377 "\n{indent}{}\n{indent}",
1379 indent = shape.indent.to_string(context.config)
1385 fn block_contains_comment(block: &ast::Block, codemap: &CodeMap) -> bool {
1386 let snippet = codemap.span_to_snippet(block.span).unwrap();
1387 contains_comment(&snippet)
1390 // Checks that a block contains no statements, an expression and no comments.
1391 // FIXME: incorrectly returns false when comment is contained completely within
1393 pub fn is_simple_block(block: &ast::Block, codemap: &CodeMap) -> bool {
1394 (block.stmts.len() == 1 && stmt_is_expr(&block.stmts[0]) &&
1395 !block_contains_comment(block, codemap))
1398 /// Checks whether a block contains at most one statement or expression, and no comments.
1399 pub fn is_simple_block_stmt(block: &ast::Block, codemap: &CodeMap) -> bool {
1400 block.stmts.len() <= 1 && !block_contains_comment(block, codemap)
1403 /// Checks whether a block contains no statements, expressions, or comments.
1404 pub fn is_empty_block(block: &ast::Block, codemap: &CodeMap) -> bool {
1405 block.stmts.is_empty() && !block_contains_comment(block, codemap)
1408 pub fn stmt_is_expr(stmt: &ast::Stmt) -> bool {
1410 ast::StmtKind::Expr(..) => true,
1415 fn is_unsafe_block(block: &ast::Block) -> bool {
1416 if let ast::BlockCheckMode::Unsafe(..) = block.rules {
1423 // A simple wrapper type against ast::Arm. Used inside write_list().
1424 struct ArmWrapper<'a> {
1425 pub arm: &'a ast::Arm,
1426 // True if the arm is the last one in match expression. Used to decide on whether we should add
1427 // trailing comma to the match arm when `config.trailing_comma() == Never`.
1431 impl<'a> ArmWrapper<'a> {
1432 pub fn new(arm: &'a ast::Arm, is_last: bool) -> ArmWrapper<'a> {
1433 ArmWrapper { arm, is_last }
1437 impl<'a> Rewrite for ArmWrapper<'a> {
1438 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1439 rewrite_match_arm(context, self.arm, shape, self.is_last)
1444 context: &RewriteContext,
1449 attrs: &[ast::Attribute],
1450 ) -> Option<String> {
1451 if arms.is_empty() {
1455 // Do not take the rhs overhead from the upper expressions into account
1456 // when rewriting match condition.
1457 let new_width = try_opt!(context.config.max_width().checked_sub(shape.used_width()));
1458 let cond_shape = Shape {
1463 let cond_shape = match context.config.control_style() {
1464 Style::Legacy => try_opt!(cond_shape.shrink_left(6)),
1465 Style::Rfc => try_opt!(cond_shape.offset_left(6)),
1467 let cond_str = try_opt!(cond.rewrite(context, cond_shape));
1468 let alt_block_sep = String::from("\n") + &shape.indent.block_only().to_string(context.config);
1469 let block_sep = match context.config.control_brace_style() {
1470 ControlBraceStyle::AlwaysNextLine => &alt_block_sep,
1471 _ if last_line_extendable(&cond_str) => " ",
1473 _ if cond_str.contains('\n') || cond_str.len() + 2 > cond_shape.width => &alt_block_sep,
1477 let nested_indent_str = shape
1479 .block_indent(context.config)
1480 .to_string(context.config);
1481 // Inner attributes.
1482 let inner_attrs = &inner_attributes(attrs);
1483 let inner_attrs_str = if inner_attrs.is_empty() {
1488 .rewrite(context, shape)
1489 .map(|s| format!("{}{}\n", nested_indent_str, s))
1493 let open_brace_pos = if inner_attrs.is_empty() {
1496 .span_after(mk_sp(cond.span.hi(), arms[0].span().lo()), "{")
1498 inner_attrs[inner_attrs.len() - 1].span().hi()
1501 let arm_indent_str = if context.config.indent_match_arms() {
1504 shape.indent.to_string(context.config)
1508 "match {}{}{{\n{}{}{}\n{}}}",
1513 try_opt!(rewrite_match_arms(
1520 shape.indent.to_string(context.config),
1524 fn arm_comma(config: &Config, body: &ast::Expr, is_last: bool) -> &'static str {
1525 if is_last && config.trailing_comma() == SeparatorTactic::Never {
1527 } else if config.match_block_trailing_comma() {
1529 } else if let ast::ExprKind::Block(ref block) = body.node {
1530 if let ast::BlockCheckMode::Default = block.rules {
1540 fn rewrite_match_arms(
1541 context: &RewriteContext,
1545 open_brace_pos: BytePos,
1546 ) -> Option<String> {
1547 let arm_shape = if context.config.indent_match_arms() {
1548 shape.block_indent(context.config.tab_spaces())
1550 shape.block_indent(0)
1551 }.with_max_width(context.config);
1553 let arm_len = arms.len();
1554 let is_last_iter = repeat(false)
1555 .take(arm_len.checked_sub(1).unwrap_or(0))
1556 .chain(repeat(true));
1557 let items = itemize_list(
1561 .map(|(arm, is_last)| ArmWrapper::new(arm, is_last)),
1563 |arm| arm.arm.span().lo(),
1564 |arm| arm.arm.span().hi(),
1565 |arm| arm.rewrite(context, arm_shape),
1570 let arms_vec: Vec<_> = items.collect();
1571 let fmt = ListFormatting {
1572 tactic: DefinitiveListTactic::Vertical,
1573 // We will add/remove commas inside `arm.rewrite()`, and hence no separator here.
1575 trailing_separator: SeparatorTactic::Never,
1576 separator_place: SeparatorPlace::Back,
1578 ends_with_newline: true,
1579 preserve_newline: true,
1580 config: context.config,
1583 write_list(&arms_vec, &fmt)
1586 fn rewrite_match_arm(
1587 context: &RewriteContext,
1591 ) -> Option<String> {
1592 let (missing_span, attrs_str) = if !arm.attrs.is_empty() {
1593 if contains_skip(&arm.attrs) {
1594 let (_, body) = flatten_arm_body(context, &arm.body);
1595 // `arm.span()` does not include trailing comma, add it manually.
1596 return Some(format!(
1598 context.snippet(arm.span()),
1599 arm_comma(context.config, body, is_last),
1604 arm.attrs[arm.attrs.len() - 1].span.hi(),
1605 arm.pats[0].span.lo(),
1607 try_opt!(arm.attrs.rewrite(context, shape)),
1610 (mk_sp(arm.span().lo(), arm.span().lo()), String::new())
1612 let pats_str = try_opt!(
1613 rewrite_match_pattern(context, &arm.pats, &arm.guard, shape).and_then(|pats_str| {
1614 combine_strs_with_missing_comments(
1629 arm.guard.is_some(),
1634 fn rewrite_match_pattern(
1635 context: &RewriteContext,
1636 pats: &[ptr::P<ast::Pat>],
1637 guard: &Option<ptr::P<ast::Expr>>,
1639 ) -> Option<String> {
1642 let pat_shape = try_opt!(shape.sub_width(5));
1644 let pat_strs = try_opt!(
1646 .map(|p| p.rewrite(context, pat_shape))
1647 .collect::<Option<Vec<_>>>()
1650 let items: Vec<_> = pat_strs.into_iter().map(ListItem::from_str).collect();
1651 let tactic = definitive_tactic(
1653 ListTactic::HorizontalVertical,
1654 Separator::VerticalBar,
1657 let fmt = ListFormatting {
1660 trailing_separator: SeparatorTactic::Never,
1661 separator_place: context.config.match_pattern_separator_break_point(),
1663 ends_with_newline: false,
1664 preserve_newline: false,
1665 config: context.config,
1667 let pats_str = try_opt!(write_list(&items, &fmt));
1670 let guard_str = try_opt!(rewrite_guard(
1674 trimmed_last_line_width(&pats_str),
1677 Some(format!("{}{}", pats_str, guard_str))
1681 // @extend: true if the arm body can be put next to `=>`
1682 // @body: flattened body, if the body is block with a single expression
1683 fn flatten_arm_body<'a>(context: &'a RewriteContext, body: &'a ast::Expr) -> (bool, &'a ast::Expr) {
1685 ast::ExprKind::Block(ref block)
1686 if !is_unsafe_block(block) && is_simple_block(block, context.codemap) =>
1688 if let ast::StmtKind::Expr(ref expr) = block.stmts[0].node {
1690 !context.config.multiline_match_arm_forces_block() &&
1691 expr.can_be_overflowed(context, 1),
1699 !context.config.multiline_match_arm_forces_block() &&
1700 body.can_be_overflowed(context, 1),
1706 fn rewrite_match_body(
1707 context: &RewriteContext,
1708 body: &ptr::P<ast::Expr>,
1713 ) -> Option<String> {
1714 let (extend, body) = flatten_arm_body(context, body);
1716 let comma = arm_comma(context.config, body, is_last);
1717 let alt_block_sep = String::from("\n") + &shape.indent.block_only().to_string(context.config);
1718 let alt_block_sep = alt_block_sep.as_str();
1719 let (is_block, is_empty_block) = if let ast::ExprKind::Block(ref block) = body.node {
1720 (true, is_empty_block(block, context.codemap))
1725 let combine_orig_body = |body_str: &str| {
1726 let block_sep = match context.config.control_brace_style() {
1727 ControlBraceStyle::AlwaysNextLine if is_block => alt_block_sep,
1731 Some(format!("{} =>{}{}{}", pats_str, block_sep, body_str, comma))
1734 let forbid_same_line = has_guard && pats_str.contains('\n') && !is_empty_block;
1735 let next_line_indent = if is_block {
1738 shape.indent.block_indent(context.config)
1740 let combine_next_line_body = |body_str: &str| {
1742 return Some(format!(
1745 next_line_indent.to_string(context.config),
1750 let indent_str = shape.indent.to_string(context.config);
1751 let nested_indent_str = next_line_indent.to_string(context.config);
1752 let (body_prefix, body_suffix) = if context.config.wrap_match_arms() {
1753 let comma = if context.config.match_block_trailing_comma() {
1758 ("{", format!("\n{}}}{}", indent_str, comma))
1760 ("", String::from(","))
1763 let block_sep = match context.config.control_brace_style() {
1764 ControlBraceStyle::AlwaysNextLine => format!("{}{}\n", alt_block_sep, body_prefix),
1765 _ if body_prefix.is_empty() => "\n".to_owned(),
1766 _ if forbid_same_line => format!("{}{}\n", alt_block_sep, body_prefix),
1767 _ => format!(" {}\n", body_prefix),
1768 } + &nested_indent_str;
1779 // Let's try and get the arm body on the same line as the condition.
1781 let orig_body_shape = shape
1782 .offset_left(extra_offset(pats_str, shape) + 4)
1783 .and_then(|shape| shape.sub_width(comma.len()));
1784 let orig_body = if let Some(body_shape) = orig_body_shape {
1785 let rewrite = nop_block_collapse(
1786 format_expr(body, ExprType::Statement, context, body_shape),
1792 if !forbid_same_line &&
1794 (!body_str.contains('\n') && body_str.len() <= body_shape.width)) =>
1796 return combine_orig_body(body_str);
1803 let orig_budget = orig_body_shape.map_or(0, |shape| shape.width);
1805 // Try putting body on the next line and see if it looks better.
1806 let next_line_body_shape = Shape::indented(next_line_indent, context.config);
1807 let next_line_body = nop_block_collapse(
1808 format_expr(body, ExprType::Statement, context, next_line_body_shape),
1809 next_line_body_shape.width,
1811 match (orig_body, next_line_body) {
1812 (Some(ref orig_str), Some(ref next_line_str))
1813 if forbid_same_line || prefer_next_line(orig_str, next_line_str) =>
1815 combine_next_line_body(next_line_str)
1817 (Some(ref orig_str), _) if extend && first_line_width(orig_str) <= orig_budget => {
1818 combine_orig_body(orig_str)
1820 (Some(ref orig_str), Some(ref next_line_str)) if orig_str.contains('\n') => {
1821 combine_next_line_body(next_line_str)
1823 (None, Some(ref next_line_str)) => combine_next_line_body(next_line_str),
1824 (None, None) => None,
1825 (Some(ref orig_str), _) => combine_orig_body(orig_str),
1829 // The `if ...` guard on a match arm.
1831 context: &RewriteContext,
1832 guard: &Option<ptr::P<ast::Expr>>,
1834 // The amount of space used up on this line for the pattern in
1835 // the arm (excludes offset).
1836 pattern_width: usize,
1837 ) -> Option<String> {
1838 if let Some(ref guard) = *guard {
1839 // First try to fit the guard string on the same line as the pattern.
1840 // 4 = ` if `, 5 = ` => {`
1841 let cond_shape = shape
1842 .offset_left(pattern_width + 4)
1843 .and_then(|s| s.sub_width(5));
1844 if let Some(cond_shape) = cond_shape {
1845 if let Some(cond_str) = guard.rewrite(context, cond_shape) {
1846 if !cond_str.contains('\n') || pattern_width <= context.config.tab_spaces() {
1847 return Some(format!(" if {}", cond_str));
1852 // Not enough space to put the guard after the pattern, try a newline.
1853 // 3 = `if `, 5 = ` => {`
1854 let cond_shape = Shape::indented(shape.indent.block_indent(context.config), context.config)
1856 .and_then(|s| s.sub_width(5));
1857 if let Some(cond_shape) = cond_shape {
1858 if let Some(cond_str) = guard.rewrite(context, cond_shape) {
1859 return Some(format!(
1861 cond_shape.indent.to_string(context.config),
1873 fn rewrite_pat_expr(
1874 context: &RewriteContext,
1875 pat: Option<&ast::Pat>,
1878 // Connecting piece between pattern and expression,
1879 // *without* trailing space.
1883 ) -> Option<String> {
1884 debug!("rewrite_pat_expr {:?} {:?} {:?}", shape, pat, expr);
1885 if let Some(pat) = pat {
1886 let matcher = if matcher.is_empty() {
1889 format!("{} ", matcher)
1892 try_opt!(try_opt!(shape.offset_left(matcher.len())).sub_width(connector.len()));
1893 let pat_string = try_opt!(pat.rewrite(context, pat_shape));
1894 let result = format!("{}{}{}", matcher, pat_string, connector);
1895 return rewrite_assign_rhs(context, result, expr, shape);
1898 let expr_rw = expr.rewrite(context, shape);
1899 // The expression may (partially) fit on the current line.
1900 // We do not allow splitting between `if` and condition.
1901 if keyword == "if" || expr_rw.is_some() {
1905 // The expression won't fit on the current line, jump to next.
1906 let nested_shape = shape
1907 .block_indent(context.config.tab_spaces())
1908 .with_max_width(context.config);
1909 let nested_indent_str = nested_shape.indent.to_string(context.config);
1910 expr.rewrite(context, nested_shape)
1911 .map(|expr_rw| format!("\n{}{}", nested_indent_str, expr_rw))
1914 fn rewrite_string_lit(context: &RewriteContext, span: Span, shape: Shape) -> Option<String> {
1915 let string_lit = context.snippet(span);
1917 if !context.config.format_strings() && !context.config.force_format_strings() {
1922 .all(|line| line.ends_with('\\'))
1924 let new_indent = shape.visual_indent(1).indent;
1925 return Some(String::from(
1929 new_indent.to_string(context.config) + line.trim_left()
1931 .collect::<Vec<_>>()
1936 return Some(string_lit);
1940 if !context.config.force_format_strings() &&
1941 !string_requires_rewrite(context, span, &string_lit, shape)
1943 return Some(string_lit);
1946 let fmt = StringFormat {
1953 config: context.config,
1956 // Remove the quote characters.
1957 let str_lit = &string_lit[1..string_lit.len() - 1];
1959 rewrite_string(str_lit, &fmt)
1962 fn string_requires_rewrite(
1963 context: &RewriteContext,
1968 if context.codemap.lookup_char_pos(span.lo()).col.0 != shape.indent.width() {
1972 for (i, line) in string.lines().enumerate() {
1974 if line.len() > shape.width {
1977 } else if line.len() > shape.width + shape.indent.width() {
1985 pub fn rewrite_call_with_binary_search<R>(
1986 context: &RewriteContext,
1988 args: &[&ast::Expr],
1995 let force_trailing_comma = if context.inside_macro {
1996 span_ends_with_comma(context, span)
2000 let closure = |callee_max_width| {
2001 // FIXME using byte lens instead of char lens (and probably all over the
2003 let callee_shape = Shape {
2004 width: callee_max_width,
2007 let callee_str = callee
2008 .rewrite(context, callee_shape)
2009 .ok_or(Ordering::Greater)?;
2017 context.config.fn_call_width(),
2018 force_trailing_comma,
2022 binary_search(1, shape.width, closure)
2025 pub fn rewrite_call(
2026 context: &RewriteContext,
2028 args: &[ptr::P<ast::Expr>],
2031 ) -> Option<String> {
2032 let force_trailing_comma = if context.inside_macro {
2033 span_ends_with_comma(context, span)
2040 &args.iter().map(|x| &**x).collect::<Vec<_>>(),
2043 context.config.fn_call_width(),
2044 force_trailing_comma,
2048 pub fn rewrite_call_inner<'a, T>(
2049 context: &RewriteContext,
2054 args_max_width: usize,
2055 force_trailing_comma: bool,
2056 ) -> Result<String, Ordering>
2058 T: Rewrite + Spanned + ToExpr + 'a,
2060 // 2 = `( `, 1 = `(`
2061 let paren_overhead = if context.config.spaces_within_parens() {
2066 let used_width = extra_offset(callee_str, shape);
2067 let one_line_width = shape
2069 .checked_sub(used_width + 2 * paren_overhead)
2070 .ok_or(Ordering::Greater)?;
2072 let nested_shape = shape_from_fn_call_style(
2075 used_width + 2 * paren_overhead,
2076 used_width + paren_overhead,
2077 ).ok_or(Ordering::Greater)?;
2079 let span_lo = context.codemap.span_after(span, "(");
2080 let args_span = mk_sp(span_lo, span.hi());
2082 let (extendable, list_str) = rewrite_call_args(
2089 force_trailing_comma,
2090 ).ok_or(Ordering::Less)?;
2092 if !context.use_block_indent() && need_block_indent(&list_str, nested_shape) && !extendable {
2093 let mut new_context = context.clone();
2094 new_context.use_block = true;
2095 return rewrite_call_inner(
2102 force_trailing_comma,
2106 let args_shape = shape
2107 .sub_width(last_line_width(callee_str))
2108 .ok_or(Ordering::Less)?;
2112 wrap_args_with_parens(context, &list_str, extendable, args_shape, nested_shape)
2116 fn need_block_indent(s: &str, shape: Shape) -> bool {
2117 s.lines().skip(1).any(|s| {
2118 s.find(|c| !char::is_whitespace(c))
2119 .map_or(false, |w| w + 1 < shape.indent.width())
2123 fn rewrite_call_args<'a, T>(
2124 context: &RewriteContext,
2128 one_line_width: usize,
2129 args_max_width: usize,
2130 force_trailing_comma: bool,
2131 ) -> Option<(bool, String)>
2133 T: Rewrite + Spanned + ToExpr + 'a,
2135 let items = itemize_list(
2139 |item| item.span().lo(),
2140 |item| item.span().hi(),
2141 |item| item.rewrite(context, shape),
2146 let mut item_vec: Vec<_> = items.collect();
2148 // Try letting the last argument overflow to the next line with block
2149 // indentation. If its first line fits on one line with the other arguments,
2150 // we format the function arguments horizontally.
2151 let tactic = try_overflow_last_arg(
2160 let fmt = ListFormatting {
2163 trailing_separator: if force_trailing_comma {
2164 SeparatorTactic::Always
2165 } else if context.inside_macro || !context.use_block_indent() {
2166 SeparatorTactic::Never
2168 context.config.trailing_comma()
2170 separator_place: SeparatorPlace::Back,
2172 ends_with_newline: context.use_block_indent() && tactic == DefinitiveListTactic::Vertical,
2173 preserve_newline: false,
2174 config: context.config,
2177 write_list(&item_vec, &fmt).map(|args_str| {
2178 (tactic != DefinitiveListTactic::Vertical, args_str)
2182 fn try_overflow_last_arg<'a, T>(
2183 context: &RewriteContext,
2184 item_vec: &mut Vec<ListItem>,
2187 one_line_width: usize,
2188 args_max_width: usize,
2189 ) -> DefinitiveListTactic
2191 T: Rewrite + Spanned + ToExpr + 'a,
2193 let overflow_last = can_be_overflowed(context, args);
2195 // Replace the last item with its first line to see if it fits with
2197 let placeholder = if overflow_last {
2198 let mut context = context.clone();
2199 if let Some(expr) = args[args.len() - 1].to_expr() {
2200 if let ast::ExprKind::MethodCall(..) = expr.node {
2201 context.force_one_line_chain = true;
2204 last_arg_shape(&context, item_vec, shape, args_max_width).and_then(|arg_shape| {
2205 rewrite_last_arg_with_overflow(&context, args, &mut item_vec[args.len() - 1], arg_shape)
2211 let mut tactic = definitive_tactic(
2213 ListTactic::LimitedHorizontalVertical(args_max_width),
2218 // Replace the stub with the full overflowing last argument if the rewrite
2219 // succeeded and its first line fits with the other arguments.
2220 match (overflow_last, tactic, placeholder) {
2221 (true, DefinitiveListTactic::Horizontal, placeholder @ Some(..)) => {
2222 item_vec[args.len() - 1].item = placeholder;
2224 _ if args.len() >= 1 => {
2225 item_vec[args.len() - 1].item = args.last()
2226 .and_then(|last_arg| last_arg.rewrite(context, shape));
2227 tactic = definitive_tactic(
2229 ListTactic::LimitedHorizontalVertical(args_max_width),
2241 context: &RewriteContext,
2244 args_max_width: usize,
2245 ) -> Option<Shape> {
2246 let overhead = items.iter().rev().skip(1).fold(0, |acc, i| {
2247 acc + i.item.as_ref().map_or(0, |s| first_line_width(s))
2249 let max_width = min(args_max_width, shape.width);
2250 let arg_indent = if context.use_block_indent() {
2251 shape.block().indent.block_unindent(context.config)
2253 shape.block().indent
2256 width: try_opt!(max_width.checked_sub(overhead)),
2262 // Rewriting closure which is placed at the end of the function call's arg.
2263 // Returns `None` if the reformatted closure 'looks bad'.
2264 fn rewrite_last_closure(
2265 context: &RewriteContext,
2268 ) -> Option<String> {
2269 if let ast::ExprKind::Closure(capture, ref fn_decl, ref body, _) = expr.node {
2270 let body = match body.node {
2271 ast::ExprKind::Block(ref block) if block.stmts.len() == 1 => {
2272 stmt_expr(&block.stmts[0]).unwrap_or(body)
2276 let (prefix, extra_offset) = try_opt!(rewrite_closure_fn_decl(
2284 // If the closure goes multi line before its body, do not overflow the closure.
2285 if prefix.contains('\n') {
2288 let body_shape = try_opt!(shape.offset_left(extra_offset));
2289 // When overflowing the closure which consists of a single control flow expression,
2290 // force to use block if its condition uses multi line.
2291 let is_multi_lined_cond = rewrite_cond(context, body, body_shape)
2292 .map(|cond| cond.contains('\n') || cond.len() > body_shape.width)
2294 if is_multi_lined_cond {
2295 return rewrite_closure_with_block(context, body_shape, &prefix, body);
2298 // Seems fine, just format the closure in usual manner.
2299 return expr.rewrite(context, shape);
2304 fn rewrite_last_arg_with_overflow<'a, T>(
2305 context: &RewriteContext,
2307 last_item: &mut ListItem,
2311 T: Rewrite + Spanned + ToExpr + 'a,
2313 let last_arg = args[args.len() - 1];
2314 let rewrite = if let Some(expr) = last_arg.to_expr() {
2316 // When overflowing the closure which consists of a single control flow expression,
2317 // force to use block if its condition uses multi line.
2318 ast::ExprKind::Closure(..) => {
2319 // If the argument consists of multiple closures, we do not overflow
2320 // the last closure.
2321 if args.len() > 1 &&
2325 .filter_map(|arg| arg.to_expr())
2326 .any(|expr| match expr.node {
2327 ast::ExprKind::Closure(..) => true,
2332 rewrite_last_closure(context, expr, shape)
2335 _ => expr.rewrite(context, shape),
2338 last_arg.rewrite(context, shape)
2341 if let Some(rewrite) = rewrite {
2342 let rewrite_first_line = Some(rewrite[..first_line_width(&rewrite)].to_owned());
2343 last_item.item = rewrite_first_line;
2350 fn can_be_overflowed<'a, T>(context: &RewriteContext, args: &[&T]) -> bool
2352 T: Rewrite + Spanned + ToExpr + 'a,
2355 .map_or(false, |x| x.can_be_overflowed(context, args.len()))
2358 pub fn can_be_overflowed_expr(context: &RewriteContext, expr: &ast::Expr, args_len: usize) -> bool {
2360 ast::ExprKind::Match(..) => {
2361 (context.use_block_indent() && args_len == 1) ||
2362 (context.config.fn_call_style() == IndentStyle::Visual && args_len > 1)
2364 ast::ExprKind::If(..) |
2365 ast::ExprKind::IfLet(..) |
2366 ast::ExprKind::ForLoop(..) |
2367 ast::ExprKind::Loop(..) |
2368 ast::ExprKind::While(..) |
2369 ast::ExprKind::WhileLet(..) => {
2370 context.config.combine_control_expr() && context.use_block_indent() && args_len == 1
2372 ast::ExprKind::Block(..) | ast::ExprKind::Closure(..) => {
2373 context.use_block_indent() ||
2374 context.config.fn_call_style() == IndentStyle::Visual && args_len > 1
2376 ast::ExprKind::Array(..) |
2377 ast::ExprKind::Call(..) |
2378 ast::ExprKind::Mac(..) |
2379 ast::ExprKind::MethodCall(..) |
2380 ast::ExprKind::Struct(..) |
2381 ast::ExprKind::Tup(..) => context.use_block_indent() && args_len == 1,
2382 ast::ExprKind::AddrOf(_, ref expr) |
2383 ast::ExprKind::Box(ref expr) |
2384 ast::ExprKind::Try(ref expr) |
2385 ast::ExprKind::Unary(_, ref expr) |
2386 ast::ExprKind::Cast(ref expr, _) => can_be_overflowed_expr(context, expr, args_len),
2391 pub fn wrap_args_with_parens(
2392 context: &RewriteContext,
2394 is_extendable: bool,
2396 nested_shape: Shape,
2398 if !context.use_block_indent() ||
2399 (context.inside_macro && !args_str.contains('\n') &&
2400 args_str.len() + paren_overhead(context) <= shape.width) || is_extendable
2402 if context.config.spaces_within_parens() && !args_str.is_empty() {
2403 format!("( {} )", args_str)
2405 format!("({})", args_str)
2410 nested_shape.indent.to_string(context.config),
2412 shape.block().indent.to_string(context.config)
2417 fn span_ends_with_comma(context: &RewriteContext, span: Span) -> bool {
2418 let snippet = context.snippet(span);
2420 .trim_right_matches(|c: char| c == ')' || c.is_whitespace())
2424 fn rewrite_paren(context: &RewriteContext, subexpr: &ast::Expr, shape: Shape) -> Option<String> {
2425 debug!("rewrite_paren, shape: {:?}", shape);
2426 let total_paren_overhead = paren_overhead(context);
2427 let paren_overhead = total_paren_overhead / 2;
2428 let sub_shape = try_opt!(
2430 .offset_left(paren_overhead)
2431 .and_then(|s| s.sub_width(paren_overhead))
2434 let paren_wrapper = |s: &str| if context.config.spaces_within_parens() && !s.is_empty() {
2435 format!("( {} )", s)
2440 let subexpr_str = try_opt!(subexpr.rewrite(context, sub_shape));
2441 debug!("rewrite_paren, subexpr_str: `{:?}`", subexpr_str);
2443 if subexpr_str.contains('\n') ||
2444 first_line_width(&subexpr_str) + total_paren_overhead <= shape.width
2446 Some(paren_wrapper(&subexpr_str))
2455 context: &RewriteContext,
2457 ) -> Option<String> {
2458 let expr_str = try_opt!(expr.rewrite(context, shape));
2460 let (lbr, rbr) = if context.config.spaces_within_square_brackets() {
2466 let offset = last_line_width(&expr_str) + lbr.len();
2467 let rhs_overhead = shape.rhs_overhead(context.config);
2468 let index_shape = if expr_str.contains('\n') {
2469 Shape::legacy(context.config.max_width(), shape.indent)
2470 .offset_left(offset)
2471 .and_then(|shape| shape.sub_width(rbr.len() + rhs_overhead))
2473 shape.visual_indent(offset).sub_width(offset + rbr.len())
2475 let orig_index_rw = index_shape.and_then(|s| index.rewrite(context, s));
2477 // Return if index fits in a single line.
2478 match orig_index_rw {
2479 Some(ref index_str) if !index_str.contains('\n') => {
2480 return Some(format!("{}{}{}{}", expr_str, lbr, index_str, rbr));
2485 // Try putting index on the next line and see if it fits in a single line.
2486 let indent = shape.indent.block_indent(context.config);
2487 let index_shape = try_opt!(Shape::indented(indent, context.config).offset_left(lbr.len()));
2488 let index_shape = try_opt!(index_shape.sub_width(rbr.len() + rhs_overhead));
2489 let new_index_rw = index.rewrite(context, index_shape);
2490 match (orig_index_rw, new_index_rw) {
2491 (_, Some(ref new_index_str)) if !new_index_str.contains('\n') => Some(format!(
2494 indent.to_string(context.config),
2499 (None, Some(ref new_index_str)) => Some(format!(
2502 indent.to_string(context.config),
2507 (Some(ref index_str), _) => Some(format!("{}{}{}{}", expr_str, lbr, index_str, rbr)),
2512 fn struct_lit_can_be_aligned(fields: &[ast::Field], base: &Option<&ast::Expr>) -> bool {
2517 fields.iter().all(|field| !field.is_shorthand)
2520 fn rewrite_struct_lit<'a>(
2521 context: &RewriteContext,
2523 fields: &'a [ast::Field],
2524 base: Option<&'a ast::Expr>,
2527 ) -> Option<String> {
2528 debug!("rewrite_struct_lit: shape {:?}", shape);
2530 enum StructLitField<'a> {
2531 Regular(&'a ast::Field),
2532 Base(&'a ast::Expr),
2536 let path_shape = try_opt!(shape.sub_width(2));
2537 let path_str = try_opt!(rewrite_path(
2545 if fields.is_empty() && base.is_none() {
2546 return Some(format!("{} {{}}", path_str));
2549 // Foo { a: Foo } - indent is +3, width is -5.
2550 let (h_shape, v_shape) = try_opt!(struct_lit_shape(shape, context, path_str.len() + 3, 2));
2552 let one_line_width = h_shape.map_or(0, |shape| shape.width);
2553 let body_lo = context.codemap.span_after(span, "{");
2554 let fields_str = if struct_lit_can_be_aligned(fields, &base) &&
2555 context.config.struct_field_align_threshold() > 0
2557 try_opt!(rewrite_with_alignment(
2561 mk_sp(body_lo, span.hi()),
2565 let field_iter = fields
2567 .map(StructLitField::Regular)
2568 .chain(base.into_iter().map(StructLitField::Base));
2570 let span_lo = |item: &StructLitField| match *item {
2571 StructLitField::Regular(field) => field.span().lo(),
2572 StructLitField::Base(expr) => {
2573 let last_field_hi = fields.last().map_or(span.lo(), |field| field.span.hi());
2574 let snippet = context.snippet(mk_sp(last_field_hi, expr.span.lo()));
2575 let pos = snippet.find_uncommented("..").unwrap();
2576 last_field_hi + BytePos(pos as u32)
2579 let span_hi = |item: &StructLitField| match *item {
2580 StructLitField::Regular(field) => field.span().hi(),
2581 StructLitField::Base(expr) => expr.span.hi(),
2583 let rewrite = |item: &StructLitField| match *item {
2584 StructLitField::Regular(field) => {
2585 // The 1 taken from the v_budget is for the comma.
2586 rewrite_field(context, field, try_opt!(v_shape.sub_width(1)), 0)
2588 StructLitField::Base(expr) => {
2590 expr.rewrite(context, try_opt!(v_shape.offset_left(2)))
2591 .map(|s| format!("..{}", s))
2595 let items = itemize_list(
2606 let item_vec = items.collect::<Vec<_>>();
2608 let tactic = struct_lit_tactic(h_shape, context, &item_vec);
2609 let nested_shape = shape_for_tactic(tactic, h_shape, v_shape);
2610 let fmt = struct_lit_formatting(nested_shape, tactic, context, base.is_some());
2612 try_opt!(write_list(&item_vec, &fmt))
2615 let fields_str = wrap_struct_field(context, &fields_str, shape, v_shape, one_line_width);
2616 Some(format!("{} {{{}}}", path_str, fields_str))
2618 // FIXME if context.config.struct_lit_style() == Visual, but we run out
2619 // of space, we should fall back to BlockIndent.
2622 pub fn wrap_struct_field(
2623 context: &RewriteContext,
2626 nested_shape: Shape,
2627 one_line_width: usize,
2629 if context.config.struct_lit_style() == IndentStyle::Block &&
2630 (fields_str.contains('\n') ||
2631 context.config.struct_lit_multiline_style() == MultilineStyle::ForceMulti ||
2632 fields_str.len() > one_line_width)
2636 nested_shape.indent.to_string(context.config),
2638 shape.indent.to_string(context.config)
2641 // One liner or visual indent.
2642 format!(" {} ", fields_str)
2646 pub fn struct_lit_field_separator(config: &Config) -> &str {
2648 config.space_before_struct_lit_field_colon(),
2649 config.space_after_struct_lit_field_colon(),
2653 pub fn rewrite_field(
2654 context: &RewriteContext,
2657 prefix_max_width: usize,
2658 ) -> Option<String> {
2659 if contains_skip(&field.attrs) {
2661 context.snippet(field.span()),
2662 context.config.max_width(),
2666 let name = &field.ident.node.to_string();
2667 if field.is_shorthand {
2668 Some(name.to_string())
2670 let mut separator = String::from(struct_lit_field_separator(context.config));
2671 for _ in 0..prefix_max_width.checked_sub(name.len()).unwrap_or(0) {
2672 separator.push(' ');
2674 let overhead = name.len() + separator.len();
2675 let expr_shape = try_opt!(shape.offset_left(overhead));
2676 let expr = field.expr.rewrite(context, expr_shape);
2678 let mut attrs_str = try_opt!(field.attrs.rewrite(context, shape));
2679 if !attrs_str.is_empty() {
2680 attrs_str.push_str(&format!("\n{}", shape.indent.to_string(context.config)));
2684 Some(e) => Some(format!("{}{}{}{}", attrs_str, name, separator, e)),
2686 let expr_offset = shape.indent.block_indent(context.config);
2689 .rewrite(context, Shape::indented(expr_offset, context.config));
2695 expr_offset.to_string(context.config),
2704 fn shape_from_fn_call_style(
2705 context: &RewriteContext,
2709 ) -> Option<Shape> {
2710 if context.use_block_indent() {
2714 .block_indent(context.config.tab_spaces())
2715 .with_max_width(context.config)
2718 shape.visual_indent(offset).sub_width(overhead)
2722 fn rewrite_tuple_in_visual_indent_style<'a, T>(
2723 context: &RewriteContext,
2729 T: Rewrite + Spanned + ToExpr + 'a,
2731 let mut items = items.iter();
2732 // In case of length 1, need a trailing comma
2733 debug!("rewrite_tuple_in_visual_indent_style {:?}", shape);
2734 if items.len() == 1 {
2736 let nested_shape = try_opt!(shape.sub_width(3)).visual_indent(1);
2737 return items.next().unwrap().rewrite(context, nested_shape).map(
2738 |s| if context.config.spaces_within_parens() {
2739 format!("( {}, )", s)
2746 let list_lo = context.codemap.span_after(span, "(");
2747 let nested_shape = try_opt!(shape.sub_width(2)).visual_indent(1);
2748 let items = itemize_list(
2752 |item| item.span().lo(),
2753 |item| item.span().hi(),
2754 |item| item.rewrite(context, nested_shape),
2756 span.hi() - BytePos(1),
2759 let item_vec: Vec<_> = items.collect();
2760 let tactic = definitive_tactic(
2762 ListTactic::HorizontalVertical,
2766 let fmt = ListFormatting {
2769 trailing_separator: SeparatorTactic::Never,
2770 separator_place: SeparatorPlace::Back,
2772 ends_with_newline: false,
2773 preserve_newline: false,
2774 config: context.config,
2776 let list_str = try_opt!(write_list(&item_vec, &fmt));
2778 if context.config.spaces_within_parens() && !list_str.is_empty() {
2779 Some(format!("( {} )", list_str))
2781 Some(format!("({})", list_str))
2785 pub fn rewrite_tuple<'a, T>(
2786 context: &RewriteContext,
2792 T: Rewrite + Spanned + ToExpr + 'a,
2794 debug!("rewrite_tuple {:?}", shape);
2795 if context.use_block_indent() {
2796 // We use the same rule as function calls for rewriting tuples.
2797 let force_trailing_comma = if context.inside_macro {
2798 span_ends_with_comma(context, span)
2808 context.config.fn_call_width(),
2809 force_trailing_comma,
2812 rewrite_tuple_in_visual_indent_style(context, items, span, shape)
2816 pub fn rewrite_unary_prefix<R: Rewrite>(
2817 context: &RewriteContext,
2821 ) -> Option<String> {
2823 .rewrite(context, try_opt!(shape.offset_left(prefix.len())))
2824 .map(|r| format!("{}{}", prefix, r))
2827 // FIXME: this is probably not correct for multi-line Rewrites. we should
2828 // subtract suffix.len() from the last line budget, not the first!
2829 pub fn rewrite_unary_suffix<R: Rewrite>(
2830 context: &RewriteContext,
2834 ) -> Option<String> {
2836 .rewrite(context, try_opt!(shape.sub_width(suffix.len())))
2843 fn rewrite_unary_op(
2844 context: &RewriteContext,
2848 ) -> Option<String> {
2849 // For some reason, an UnOp is not spanned like BinOp!
2850 let operator_str = match *op {
2851 ast::UnOp::Deref => "*",
2852 ast::UnOp::Not => "!",
2853 ast::UnOp::Neg => "-",
2855 rewrite_unary_prefix(context, operator_str, expr, shape)
2858 fn rewrite_assignment(
2859 context: &RewriteContext,
2862 op: Option<&ast::BinOp>,
2864 ) -> Option<String> {
2865 let operator_str = match op {
2866 Some(op) => context.snippet(op.span),
2867 None => "=".to_owned(),
2870 // 1 = space between lhs and operator.
2871 let lhs_shape = try_opt!(shape.sub_width(operator_str.len() + 1));
2872 let lhs_str = format!(
2874 try_opt!(lhs.rewrite(context, lhs_shape)),
2878 rewrite_assign_rhs(context, lhs_str, rhs, shape)
2881 // The left hand side must contain everything up to, and including, the
2882 // assignment operator.
2883 pub fn rewrite_assign_rhs<S: Into<String>>(
2884 context: &RewriteContext,
2888 ) -> Option<String> {
2889 let lhs = lhs.into();
2890 let last_line_width = last_line_width(&lhs) - if lhs.contains('\n') {
2891 shape.indent.width()
2895 // 1 = space between operator and rhs.
2896 let orig_shape = try_opt!(shape.offset_left(last_line_width + 1));
2897 let rhs = try_opt!(choose_rhs(
2901 ex.rewrite(context, orig_shape)
2907 context: &RewriteContext,
2910 orig_rhs: Option<String>,
2911 ) -> Option<String> {
2913 Some(ref new_str) if !new_str.contains('\n') => Some(format!(" {}", new_str)),
2915 // Expression did not fit on the same line as the identifier.
2916 // Try splitting the line and see if that works better.
2917 let new_shape = try_opt!(
2919 shape.block().indent.block_indent(context.config),
2921 ).sub_width(shape.rhs_overhead(context.config))
2923 let new_rhs = expr.rewrite(context, new_shape);
2924 let new_indent_str = &new_shape.indent.to_string(context.config);
2926 match (orig_rhs, new_rhs) {
2927 (Some(ref orig_rhs), Some(ref new_rhs)) if prefer_next_line(orig_rhs, new_rhs) => {
2928 Some(format!("\n{}{}", new_indent_str, new_rhs))
2930 (None, Some(ref new_rhs)) => Some(format!("\n{}{}", new_indent_str, new_rhs)),
2931 (None, None) => None,
2932 (Some(ref orig_rhs), _) => Some(format!(" {}", orig_rhs)),
2938 fn prefer_next_line(orig_rhs: &str, next_line_rhs: &str) -> bool {
2939 fn count_line_breaks(src: &str) -> usize {
2940 src.chars().filter(|&x| x == '\n').count()
2943 !next_line_rhs.contains('\n') ||
2944 count_line_breaks(orig_rhs) > count_line_breaks(next_line_rhs) + 1
2947 fn rewrite_expr_addrof(
2948 context: &RewriteContext,
2949 mutability: ast::Mutability,
2952 ) -> Option<String> {
2953 let operator_str = match mutability {
2954 ast::Mutability::Immutable => "&",
2955 ast::Mutability::Mutable => "&mut ",
2957 rewrite_unary_prefix(context, operator_str, expr, shape)
2961 fn to_expr(&self) -> Option<&ast::Expr>;
2962 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool;
2965 impl ToExpr for ast::Expr {
2966 fn to_expr(&self) -> Option<&ast::Expr> {
2970 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2971 can_be_overflowed_expr(context, self, len)
2975 impl ToExpr for ast::Ty {
2976 fn to_expr(&self) -> Option<&ast::Expr> {
2980 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2981 can_be_overflowed_type(context, self, len)
2985 impl<'a> ToExpr for TuplePatField<'a> {
2986 fn to_expr(&self) -> Option<&ast::Expr> {
2990 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2991 can_be_overflowed_pat(context, self, len)
2995 impl<'a> ToExpr for ast::StructField {
2996 fn to_expr(&self) -> Option<&ast::Expr> {
3000 fn can_be_overflowed(&self, _: &RewriteContext, _: usize) -> bool {
3005 impl<'a> ToExpr for MacroArg {
3006 fn to_expr(&self) -> Option<&ast::Expr> {
3008 &MacroArg::Expr(ref expr) => Some(expr),
3013 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
3015 &MacroArg::Expr(ref expr) => can_be_overflowed_expr(context, expr, len),
3016 &MacroArg::Ty(ref ty) => can_be_overflowed_type(context, ty, len),
3017 &MacroArg::Pat(..) => false,